Fail early with Java > 1.7 as the tests currently fail with such versions

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1763567 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index 876e185..9c8c5b0 100644
--- a/pom.xml
+++ b/pom.xml
@@ -105,7 +105,27 @@
                     </execution>
                 </executions>
             </plugin>
-          </plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-enforcer-plugin</artifactId>
+                <version>1.4.1</version>
+                <executions>
+                    <execution>
+                        <id>enforce-java</id>
+                        <goals>
+                            <goal>enforce</goal>
+                        </goals>
+                        <configuration>
+                            <rules>
+                            <requireJavaVersion>
+                                <version>[1.7,1.8)</version>
+                            </requireJavaVersion>
+                            </rules>    
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>          
+        </plugins>
     </build>   
 
     <dependencies>